Lori J. West

ABO-Incompatible heart transplantation in infants

BACKGROUND Transplantation of hearts from ABO-incompatible donors is contraindicated because of the risk of hyperacute rejection mediated by preformed antibodies in the recipient to blood-group antigens of the donor. This contraindication may not apply to newborn infants, who do not yet produce antibodies to T-cell-independent antigens, including the major blood-group antigens. METHODS We studied 10 infants 4 hours to 14 months old (median, 2 months) who had congenital heart disease or cardiomyopathy and who received heart transplants from donors of incompatible blood type between 1996 and 2000. Serum isohemagglutinin titers were measured before and after transplantation. Plasma exchange was performed during cardiopulmonary bypass; no other procedures for the removal of antibodies were used. Standard immunosuppressive therapy was given, and rejection was monitored by means of endomyocardial biopsy. The results were compared with those in 10 infants who received heart transplants from ABO-compatible donors. RESULTS The overall survival rate among the 10 recipients with ABO-incompatible donors was 80 percent, with 2 early deaths due to causes presumed to be unrelated to ABO incompatibility. The duration of follow-up ranged from 11 months to 4.6 years. Two infants had serum antibodies to antigens of the donors blood group before transplantation. No hyperacute rejection occurred; mild humoral rejection was noted at autopsy in one of the infants with antibodies. No morbidity attributable to ABO incompatibility has been observed. Despite the eventual development of antibodies to antigens of the donors blood group in two infants, no damage to the graft has occurred. Because of the use of ABO-incompatible donors, the mortality rate among infants on the waiting list declined from 58 percent to 7 percent. CONCLUSIONS ABO-incompatible heart transplantation can be performed safely during infancy before the onset of isohemagglutinin production; this technique thus contributes to a marked reduction in mortality among infants on the waiting list.

Report from a consensus conference on antibody-mediated rejection in heart transplantation

BACKGROUND The problem of AMR remains unsolved because standardized schemes for diagnosis and treatment remains contentious. Therefore, a consensus conference was organized to discuss the current status of antibody-mediated rejection (AMR) in heart transplantation. METHODS The conference included 83 participants (transplant cardiologists, surgeons, immunologists and pathologists) representing 67 heart transplant centers from North America, Europe, and Asia who all participated in smaller break-out sessions to discuss the various topics of AMR and attempt to achieve consensus. RESULTS A tentative pathology diagnosis of AMR was established, however, the pathologist felt that further discussion was needed prior to a formal recommendation for AMR diagnosis. One of the most important outcomes of this conference was that a clinical definition for AMR (cardiac dysfunction and/or circulating donor-specific antibody) was no longer believed to be required due to recent publications demonstrating that asymptomatic (no cardiac dysfunction) biopsy-proven AMR is associated with subsequent greater mortality and greater development of cardiac allograft vasculopathy. It was also noted that donor-specific antibody is not always detected during AMR episodes as the antibody may be adhered to the donor heart. Finally, recommendations were made for the timing for specific staining of endomyocardial biopsy specimens and the frequency by which circulating antibodies should be assessed. Recommendations for management and future clinical trials were also provided. CONCLUSIONS The AMR Consensus Conference brought together clinicians, pathologists and immunologists to further the understanding of AMR. Progress was made toward a pathology AMR grading scale and consensus was accomplished regarding several clinical issues.

Donor-specific B-cell tolerance after ABO-incompatible infant heart transplantation

Although over 50 years have passed since its first laboratory description, intentional induction of immune tolerance to foreign antigens has remained an elusive clinical goal. We previously reported that the requirement for ABO compatibility in heart transplantation is not applicable to infants. Here, we show that ABO-incompatible heart transplantation during infancy results in development of B-cell tolerance to donor blood group A and B antigens. This mimics animal models of neonatal tolerance and indicates that the human infant is susceptible to intentional tolerance induction. Tolerance in this setting occurs by elimination of donor-reactive B lymphocytes and may be dependent upon persistence of some degree of antigen expression. These findings suggest that intentional exposure to nonself A and B antigens may prolong the window of opportunity for ABO-incompatible transplantation, and have profound implications for clinical research on tolerance induction to T-independent antigens relevant to xenotransplantation.

The 2013 International Society for Heart and Lung Transplantation Working Formulation for the standardization of nomenclature in the pathologic diagnosis of antibody-mediated rejection in heart transplantation

During the last 25 years, antibody-mediated rejection of the cardiac allograft has evolved from a relatively obscure concept to a recognized clinical complication in the management of heart transplant patients. Herein we report the consensus findings from a series of meetings held between 2010-2012 to develop a Working Formulation for the pathologic diagnosis, grading, and reporting of cardiac antibody-mediated rejection. The diagnostic criteria for its morphologic and immunopathologic components are enumerated, illustrated, and described in detail. Numerous challenges and unresolved clinical, immunologic, and pathologic questions remain to which a Working Formulation may facilitate answers.

LYMPHOPROLIFERATIVE DISORDERS AFTER ORGAN TRANSPLANTATION IN CHILDREN

BACKGROUND After organ transplant, patients are at risk of posttransplant lymphoproliferative disorders (PTLD). The purpose of this study was to analyze 26 pediatric cases of PTLD observed at our institution between 1988 and 1996, and to evaluate the validity of the Society for Hematopathology Workshop (SHPW) 1997 classification in our patient population. METHODS Charts were reviewed for analysis of incidence, clinical course, and outcome. Tissue samples were classified by a pathologist according to SHPW recommendations. RESULTS By morphology, 20 were monomorphic, 5 polymorphic, and 1 hyperplastic. Assessment of lineage by morphology, molecular studies, and immunophenotyping did not correlate in six cases. By immunophenotyping, 12 were B cell, 4 T cell, 8 mixed B/T cells, and 2 undetermined. The 20 patients evaluable for treatment efficacy were treated with various therapeutic combinations, including immunosuppressive drug reduction, acyclovir/ganciclovir, interferon-alpha, immunoglobulins, surgery, and local irradiation. No patient received systemic chemotherapy. Thirteen patients achieved complete remission and 3, partial; 1 died 5 days after starting therapy, and 3 of progressive disease. Adverse prognostic factors included low platelet or neutrophil counts; stage III-IV and SHPW morphology were marginally significant. CONCLUSIONS The majority of patients eligible for treatment can be cured with immunosuppressive drug reduction and antiviral drugs, along with surgery and irradiation when indicated. Systemic chemotherapy or innovative approaches may have a role in unresponsive cases. Morphologic SHPW grouping is feasible and seems to have clinical relevance. However, correlation with clonality and immunophenotyping is not always possible, necessitating modifications including segregation of descriptive morphology from clonality and cell origin.

Report from a consensus conference on the sensitized patient awaiting heart transplantation.

A consensus conference took place on April 8, 2008 to assess the current status of sensitization in the pre–heart transplant patient, the use and efficacy of desensitization therapies, and the outcome of desensitized patients after heart transplantation. The conference had 71 participants (transplant cardiologists, surgeons, immunologists and pathologists; see Appendix) representing 51 heart transplant centers from North America, Europe, Asia and Australia. Prior to the conference, survey data (regarding the sensitized patient) were submitted by 23 of the 51 centers participating in the conference (Table 1).

Defining critical windows in the development of the human immune system.

Identifying critical windows in immune system development is crucial for determination of either safety or vulnerability to exposure to specific agents during rapidly changing phases of ontogeny. These phases in the human range from postconception early gestation through adolescence. A detailed understanding of these windows will facilitate avoidance of environmental toxins as well as allow improved planning for unavoidable exposures. Critical windows of immune development will be influenced by concomitant development, maturation and growth of other organ systems, thus the influence of potentially toxic exposures must be determined within a co-ordinated multisystem and multidisciplinary approach.

Risk factors for post-transplant lymphoproliferative disorder in pediatric patients : A case-control study

Abstract:  Post‐transplant Lymphoproliferative Disorder (PTLD) because of the Epstein–Barr Virus (EBV) is a major concern after pediatric transplantation. The group at greatest risk is EBV‐seronegative recipients who receive EBV‐seropositive organs. Additional risk factors remain to be determined, including those among EBV‐seropositive recipients. In this case‐control study, PTLD cases were biopsy‐proven over a period of 4 yr (1997–2000, inclusive). Each case was matched with 2 controls, based on the type of organ transplanted and the period of transplantation (±1 yr). Variables compared between cases and controls included those relating to the clinical and virologic profiles and immunosuppressive therapy. Twenty‐two cases of PTLD were diagnosed during the study period. PTLD cases occurred at a median of 22.8 months post‐transplantation (range 1–131). The median age of cases was 26.2 months (range 6.1–194) compared with 47.4 months (range 0.8–202.2) for controls (p = 0.93). Cases had a higher mean baseline EBV load compared with controls (3.1 log10 (s.d. ± 1.0) vs. 1.6 log10/106 PBMCs (s.d. ± 1.4), with every 1 log increase in viral load resulting in a three times increase in the likelihood of PTLD (p < 0.007). Close to one in four cases of PTLD were EBV‐seropositive pretransplantation. These seropositive recipients tended to be older patients with a trend to a worse outcome compared with their seronegative counterparts. The occurrence of PTLD was not associated with the use of any specific immunosuppressants. A significant proportion of PTLD cases occurred among EBV‐seropositive transplant recipients, with a tendency towards an unfavorable outcome. Besides EBV‐seronegative recipients who receive seropositive organs, some EBV‐seropositive pediatric patients are at risk of PTLD. Additional studies are warranted to further define the factors associated with PTLD in EBV‐seropositive transplant recipients.

Ambulatory blood pressure monitoring and left ventricular mass and function after successful surgical repair of coarctation of the aorta

Late cardiovascular morbidity and mortality remain significant despite apparently successful surgical repair of aortic coarctation. Alterations in cardiac function have been reported in normotensive patients who have had successful repair, the reasons for which remain unclear. This study addresses the relation between ambulatory blood pressure measurements and alterations in left ventricular performance in 20 patients with normotension at rest after successful repair of aortic coarctation. Exercise testing, ambulatory blood pressure monitoring and two-dimensional echocardiographic studies in 13 boys and 7 girls (mean age 14.2 +/- 2.31 and 14.7 +/- 3 years, respectively) who had no evidence of recoarctation were compared with the findings in 20 matched control subjects. No difference was found in systolic blood pressure at rest or peak exercise between patients and control subjects. Male patients developed a significant arm/leg gradient at peak exercise. Systolic ambulatory blood pressure was higher throughout the day in the male group. In the female group, systolic blood pressure was higher only during sleep. No difference was found in diastolic blood pressure or heart rate. The transverse aortic arch was smaller and the left ventricular mass greater in all patients. The relation of wall stress to rate-corrected velocity of shortening was 2 SD above normal in 8 of the 20 patients, suggesting that some have enhanced contractility. The E/A ratio on the atrial echocardiogram was significantly reduced in the patient group. Successfully treated patients who are normotensive at rest after operation are still at risk for developing end organ damage, which is probably explained by incipient mild hypertension documented by ambulatory blood pressure monitoring.

The use of immunoglobulin therapy for patients undergoing solid organ transplantation: an evidence-based practice guideline.

This guideline for the use of immunoglobulin (IG) for sensitized patients undergoing solid organ transplantation (SOT) is an initiative of the Canadian Blood Services and the National Advisory Committee on Blood and Blood Products of Canada to (1) provide guidance for Canadian practitioners involved in the care of patients undergoing SOT and transfusion medicine specialists on the use of IG and (2) standardize care, limit adverse events, and optimize patient care. A systematic expert and bibliography literature search up to July 2008 was conducted, with 791 literature citations and 45 reports reviewed. To validate the recommendations, the guideline was sent to physicians involved in SOT in Canada and a patient representative. The recommendations identify (1) sensitized patients undergoing SOT that would have a better survival and decreased morbidity by receiving IG preoperatively, postoperatively, and for the treatment of organ rejection; (2) patients who may not have any benefit from receiving IG; and (3) potential adversities to IG.